Abstract
Background Electrocardiogram (ECG) changes in patients with subarachnoid hemorrhage (SAH) are
frequent. ST- and/or T-wave changes in ECG seem to predominate.
Study Aims To investigate the ion channel mechanisms of SAH-induced ventricular excitation-contraction
coupling changes and the possible protective effect of N-acetylcysteine (NAC).
Methods Three groups of rabbits were used for the experiments. In two groups, SAH was induced
by replacing the cerebrospinal fluid (CSF) with fresh autologous blood. In the control
group, CSF was replaced with isotonic saline. In one SAH group, NAC was administered
daily beginning at SAH induction. On day 5, ventricular action potentials, ionic currents,
contractions, and intracellular free ion concentrations were recorded from the myocytes.
Results In the SAH group, no change was found in the sodium currents, but the transient outward
potassium currents were depressed, rapid repolarizing currents were increased, and
t-type calcium currents were increased. Contractions and the intracellular free calcium
concentration were depressed. NAC treatment, in contrast, not only restores these
electrical remodeling changes but also the contractile abnormalities in the cardiac
myocytes.
Conclusion The changes in the action potential duration can be attributed to the measured ionic
current changes. However, the exact mechanism, other than the oxidative stress, by
which the NAC treatment protects the cardiac muscle needs additional investigations.
Keywords
action potential - ionic currents - myocyte - N- acetylcysteine - subarachnoid hemorrhage
